Salaah

Making niyyat of four rakaats and making salaam after two rakaats

Q: If a person commences performing four rakaats sunnat ghair muakkadah, before Asr or Esha, but due to the jamaat salaah starting, he only performs two rakaats instead of four, then will he need to perform these four rakaats later on after the jamaat? (The reason I am asking is that I have read that once we start salaah, even a nafl salaah, it becomes waajib to complete it.)

Repeating Esha fardh and sunnat if the fardh was invalid

Q:

1. If we perform Esha Fard, sunnat and witr and nafl but after the time of the prayer has expired we realized that the fard was not valid, what qadha do we need to offer (from the Fard, sunnat, witr and nafl)?

2. If we perform Esha Fard, sunnat, witr and nafl and before the time has expired, we realized that the fard was not valid, what do we we need to repeat (from Fard, sunnat, witr and nafl)?

Raising the index finger during tashahud

Q: I have come across a Hadith narrated by Wail ibn Hujr (Radhiyallahu Anhu) on the description of the prophetic prayer in Abu Dawood, and there I found that we should raise the index finger from the starting of tashahud to the end of salah and we should slightly move (shivering/vibrating it in an infinitesimally small distance) but the people of my community raise their finger only while saying ash hadu an la I laha... (I know both of it can be done, but I would like to prefer the authenticity one) and so I did it up to now! Hanafi/Shafi school do it I think so, but could you please tell me what to do now.

Moving one's lips while reciting duas in salaah

Q: I heard from a shaik that one should move his lips while reciting azkaar in salaah or in general, and he gave the example of "one will not get sin if they think of sinning except they say or act on it. and the shaik said that so similar the good deeds!"

a. Once I read in a hadith that the Prophet (Sallallahu Alaihi Wasallam) never moved his lips in Salatul Asr. (I was not aware of the authenticity of that and I also remember that I read it from Sahih Muslim/Bukhari). 

b. I heard from another shaik that if someone around you recites anything only by moving his lips or some phrase with a sound and some without, then he said that one should warn such a person to stop it or read it clearly and loudly, if not then we have to tell them that "you are a witch person and will reveal it to everyone if you don't, (because it is an act of witches or magicians, the shaik said)" now which is correct and in which situations?

Performing salaah with a distance between musallis and with a mask

Q: Prayers are offered in Masajid these days with distances between musallees being about one meter and leaving the alternate saff empty. Also, we need to wear a thin mask during prayers. This way the nose does not get in contact with the ground.

1. Are our prayers valid with distances in between?

2. Are our prayers valid with a face mask on?